Within the last fifty years the art of metal casting has made significant advances with the advent of rotary die casting machines and continuous strip casters. While advances have been made in the die casting machines only a few changes have occurred in the techniques for delivery of the molten metal to the machine. The industry still delivers the molten metal to the machine in heated ladles or heated tiltable crucibles. Several innovations which seemed logical, e.g. molten metal pumps based on the Einstein design, heated troughs and/or pipes, shot size delivery apparatus and the like have not been universally employed. Some of the disadvantages of such art equipment are that for the higher melting metals, e.g. magnesium or aluminum, the pumps have required external cooling or extended shafts to place the motor away from the high heat zone of the crucible or melting pot. Each of these aspects has apparent problems obvious to those skilled in the art. Likewise, heated troughs and/or piping has been employed to deliver the molten metal from the pump or a tiltable crucible or raised plugged crucible. These containing and directing pipes and troughs usually are heated by gas fired burners or electrical resistance heating technique through the metal. The disadvantage of each technique is obvious, the gas fired heaters create an undesirable work place environment and the resistance heaters are difficult to control when a molten metal is the resistance.
In addition, most of the systems expose the molten metal to the ambient atmosphere permitting oxidation of the metal resulting in metal oxide impurities in the castings and generally poor quality castings. The extent of oxidation losses is particularly detrimental to magnesium castings.
Further, none of these systems is readily controlled to enable repetitive shot or draw conditions to be automatically uniform.